Isuzu 1999 RODEO Workshop Manual page 440

The master cylinder contains two pistons that supply the
hydraulic pressure for a dual–circuit braking system. The
primary piston provides the fluid pressure to the front
brakes, while the secondary piston provides the fluid
pressure to the rear brakes. If the pressure is lost from
either system, the remaining system will function to stop
the vehicle.
Brake Booster
This booster is a tandem vacuum unit with a diaphragm
effective diameter 205mm + 230mm. In normal operating
mode, with the service brakes in the released position,
the tandem vacuum booster operates with vacuum on
both sides of its diaphragms. When the brakes are
applied, air at atmospheric pressure is admitted to one
side of each diaphragm to provide the power assist.
When the service brake is released, the atmospheric air is
shut off from the one side of each diaphragm. The air is
then drawn from the booster through the vacuum check
valve to the vacuum source.
POWER–ASSISTED BRAKE SYSTEM
CAUTION:
1. The master cylinder is not repairable. If found
defective, it must be replaced as a complete
assembly.
2. If any hydraulic component is removed or
disconnected, it may be necessary to bleed all or
part of the brake system. (Refer to "Bleeding
Brake Hydraulic System" in this section.)
3. The torque values
unlubricated fasteners.
4. Perform service operations on a clean bench free
from all mineral oil materials.
CAUTION:
1. If any hydraulic component is removed or
disconnected, it may be necessary to bleed all or
part of the brake system.
2. The torque values
unlubricated fasteners.
3. The vacuum booster is not repairable and must be
replaced as complete assembly.
5C–3
specified are for dry,
331RS001
specified are for dry,